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AISC 341-22 Eccentrically Braced Frame — Link Beam

§F3 I-shaped link: V_p = 0.6F_y(d − 2t_f)t_w, M_p = F_yZ, V_n = min(V_p, 2M_p/e); classification by e/(M_p/V_p) (shear ≤ 1.6, flexural ≥ 2.6); allowed link rotation 0.08 → 0.02 rad; adjusted link shear 1.25R_yV_n for capacity design. Axial-force reduction (P_r > 0.15P_y) is flagged, not computed.

Link section

Grade

d in

t_f in

t_w in

Z_x in³

A_g in²

Link length e in

Demand (optional)

P_r in link kip

V_u kip

Bay width L (link at mid-span) in

Plastic story drift ratio θ_p

Results

A_lw · V_p · M_p—

e/(M_p/V_p) · link type—

V_n · φV_n (φ = 0.9) kip—

Adjusted link shear 1.25R_yV_n (capacity design)—

Link rotation γ_p = (L/e)θ_p vs allowed §F3.4a—

φV_n ≥ V_u?—

§F3Shear links e ≤ 1.6M_p/V_p (rotation 0.08 rad), flexural links e ≥ 2.6M_p/V_p (0.02 rad), linear between. AISC 341-22 defines the link rotation at the design earthquake displacement.

CapacityMembers outside the link are designed for the adjusted link shear strength 1.25R_yV_n (I-shaped links) — tests show the true overstrength can be larger.

Rotationγ_p = (L/e)θ_p is the usual kinematic estimate for a link at mid-span (split-K / chevron EBF); other configurations need their own geometry.

VerifyHand calculation (regression test): W18×35, e = 36 in → A_lw 5.055 in², V_p 151.65 kip, M_p/V_p 21.93 in, ratio 1.642 (intermediate), allowed rotation 0.0775 rad, φV_n 136.5, adjusted 208.5 kip. Sources: Elsevier 2025 (citing AISC 341-22), Elsevier 2023.

ScopeI-shaped links without significant axial force. Link stiffeners, lateral bracing of the link and box links are not included.

Preliminary calculation tool. Final design requires the full text of the referenced standard (see the sources on this page) and review by a licensed PE.